Breeding pattern of Oreochromis niloticus (Linnaeus, 1758) (Pisces: Cichlidae) versus native congeneric species, Oreochromis macrochir (Boulinger, 1912) in the upper Kabompo River, northwest of Zambia

Investigating the determinants of reproductive biology of fishes is an essential component of biological research. Breeding pattern was investigated to determine the impact of exotic Oreochromis niloticus on the native congeneric Oreochromis macrochir in the upper Kabompo River. Gonado-somatic index and sex ratio was used to investigate the breeding pattern in both invaded (where O. niloticus is present) and uninvaded (where O. niloticus is absent) sections of the river. Oreochromis macrochir was the only native congeneric species found in both sections. Results showed that the overall gonado-somatic index means for both sexes of O. macrochir in both sections were similar. For O. niloticus in invaded section indicated all year reproduction though reduced spawning in cold season (May-June), but with increased spawning activity in wet season (February-March). In O. macrochir, males and females were found breeding in both dry and wet seasons only, as for cold season no reproduction was recorded. Sex ratio (females: males) was 1:1.3 and 1:1.7 for O. niloticus and O. macrochir respectively, and both significantly deviated from the sex ratio of 1:1 (ꭓ2=8.42 and 9.37; p<0.05). Oreochromis niloticus formed the most abundant fish caught 221(63.5%) than O. macrochir 127(36.5%). Our study has revealed that O. niloticus was able to spawn in all seasons with 23% higher breeding population than O. macrochir, which explains the suppression in the abundance. We expect O. niloticus to invade further downstream of the Kabompo River due to natural dispersion.

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REPRODUCTIVE ASPECTS OF SCALLOPED PERCHLET, Ambassis nalua (HAMILTON, 1822) IN PABEAN BAY INDRAMAYU, WEST JAVA

Jurnal Ilmu dan Teknologi Kelautan Tropis ◽

10.28930/jitkt.v9i1.17921 ◽

2017 ◽

Vol 9 (1) ◽

pp. 113

Author(s):

Nisha Desfi Arianti ◽

M.F. Rahardjo ◽

Ahmad Zahid

Keyword(s):

Sex Ratio ◽

Sampling Period ◽

Spawning Season ◽

West Java ◽

Fish Samples ◽

Length Range ◽

Males And Females ◽

Mature Fish ◽

First Maturity ◽

Somatic Index

ABSTRACTScalloped perchlet, Ambassis nalua, is one of fishes in Pabean Bay, Indramayu. This research aims to determine the reproductive aspects of Ambassis nalua in Pabean Bay Indramayu including sex ratio, spawning season, first maturity, fecundity and spawning pattern. Fish samples were collected by trap net and trammel net at three sites in Pabean Bay from April to October 2015. A total of 424 of A. nalua were caught, consist of 114 males and 310 females; with total length ranged from 38.04 to 112.63 mm and total weight ranged from 0.37 to 25.44 g. Sex ratio of mature fish was 1:1.9. The mature males and females were found in every month of sampling period. The gonado-somatic index (GSI) ranged from 0.40 to 0.83 and 2.36 to 4.54 for male and female, respectively. The peak of spawning season was found in September. The first maturity (Lm50) for male and female were 79.17 mm and 91.25 mm, respectively. The fecundity varied from 3,451–32,465 eggs. Egg diameter distribution shows that spawning pattern of A. nalua was batch spawner. Keywords: Ambassis nalua, spawning season, sex ratio, reproduction

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Anacondas’ Tales

Anaconda ◽

10.1093/oso/9780199732876.003.0004 ◽

2020 ◽

pp. 49-78

Author(s):

Jesús A. Rivas

Keyword(s):

Sex Ratio ◽

Population Model ◽

Lower Number ◽

The Other ◽

Wet Season ◽

Death Rates ◽

In The Wild ◽

Males And Females ◽

Number Of Males ◽

Very High

This chapter examines the lives and tribulations of anacondas. Anacondas, like humans, produce the same number of males and females because the sex ratio is determined by sexual chromosomes. If the sexes start out equally abundant, why would there be so many more males out there in the wild? In some vertebrates one sex or the other disperses away from the area they were born. However, the author does not believe migration plays a significant role with anacondas. For starters, males are the sex with the wanderlust, not females. As such, this would not account for the lower number of females. Moreover, migration should not be very high due to the fact that the study site is the only region that holds water, so animals might move out in the wet season, but they would likely come back in the dry season, when the author did most of the sampling. If migration is not the answer for the uneven sex ratio, one is left with mortality of females as the only explanation. If females suffered higher death rates, that could explain the male bias in the population that the model estimated. Looking further into the results of the population model, the author found that females have a lower estimated survival than males. The chapter then considers the reasons females have higher mortality. The large expenditure in reproduction females incur might result in death not only as a result of predation but also during or after feeding due to weakening.

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Some Spawning Performance Parameters of Cultured Nile Tilapia Oreochromis niloticus, under Brackish Water

Aquatic Science and Technology ◽

10.5296/ast.v7i1.13660 ◽

2018 ◽

Vol 7 (1) ◽

pp. 8

Author(s):

Nassrin Mashaii ◽

Farhad Rajabipour ◽

Mohamad Jafari ◽

Mohammad Mohammadi ◽

Habib Sarsangi ◽

...

Keyword(s):

Sex Ratio ◽

Oreochromis Niloticus ◽

Stocking Density ◽

Water Salinity ◽

Performance Parameters ◽

Nile Tilapia Oreochromis Niloticus ◽

Cultured Fish ◽

The World ◽

Egg Diameter ◽

The Impact

Tilapia is one of the most important cultured fish in the world. However, the gap between seed supplies and farmers' demand is one of the serious limitations for tilapia culturists. Notice about different effective agents on tilapia reproduction might be useful for increasing of production and better management of tilapia hatcheries. In the present study, higher efficiency of tilapia Oreochromis niloticus hatchery was considered based on the impact of sex ratio, stocking density, photoperiod, water salinity and replacement period on spawning performance. Sex ratios 1:1, 1:4 and 1:7 (Male: Female), stocking densities 2, 3.5 and 5 fish/m3, photoperiods 6:18, 12:12 and 18:6 (Light:Dark), water salinities 12, 8, 4 and 0 ppt, also10 and 15 days replacement of breeders were studied. Fecundity,breeder and egg per day,spawning intervals, egg diameter and weight were investigated. Results showed stocking density 5 fish/m3, photoperiod 12:12, 8 ppt water salinity and 10 days replacement had better performance. Sex ratio treatments had similar performance.

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Short term changes in sex ratio and density alter coercive male mating tactics

Behaviour ◽

10.1163/000579510x519495 ◽

2010 ◽

Vol 147 (11) ◽

pp. 1431-1442 ◽

Cited By ~ 7

Author(s):

James Cureton II ◽

Raelynn Deaton ◽

Rachel Martin

Keyword(s):

Sex Ratio ◽

Reproductive Activity ◽

Operational Sex Ratio ◽

Mating Frequency ◽

Male Mating ◽

Mating Tactics ◽

Short Term ◽

Classic Theory ◽

Males And Females ◽

The Impact

AbstractShort term fluctuations in operational sex ratio (OSR) and density can strongly influence male mating, often exacerbating conflict between males and females. Livebearing fishes of the genus Gambusia are ideal for investigating sexual conflict because males of all sizes mate coercively. In this study, we tested how short-term fluctuations in OSR and density influence coercive male mating behaviours. Specifically, we tested the prediction that as OSR becomes more female biased, males will mate with all available females. In contrast, as OSR becomes more male biased, male aggression will inhibit mating frequency. As predicted, males mated with more females as the number of available females increased. Moreover, males were less aggressive as the proportion of females increased and more aggressive as the number of males increased. This resulted in an inverse relationship between mating and aggression with OSR and density. Coercive males attempt to maximize their reproductive success by mating with all available females, which supports classic theory on the impact of OSR and density on reproductive activity.

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A PRELUDE ON THE BIOLOGY OF PUNTIUS AMPHIBIUS

Kongunadu Research Journal ◽

10.26524/krj179 ◽

2017 ◽

Vol 4 (1) ◽

pp. 69-72

Author(s):

Munisha Murali S ◽

Sheeba S

Keyword(s):

Sex Ratio ◽

Feeding Habits ◽

Monsoon Season ◽

Gut Content ◽

Significant Difference ◽

Active Feeding ◽

Food And Feeding ◽

Males And Females ◽

Relationship Of ◽

Somatic Index

Knowledge on fish biology is essential for improving aquaculture. The present study was focused on the biology of Puntiusamphibius. The fishes were collected from a freshwater body in parlance known as “Arappa”, located in Thalikulam at Thrissur district in Kerala. This water body is in the vicinity of the sea anddebouches into the marine during monsoon season. In the present investigation 106 fishes were collected during March to August 2006. The study revealed that there was no significant difference observed among the length weight relationship of males and females. Composition of gut content showed that it is a selectivefeeder of Bacillariophyceae and a pronounced omnivore. The gastro-somatic index of female and male was high during May indicating the active feeding during breeding.The sex ratio between males and females was variable and female dominated over males. The fecundity of fish was proportional to the weight of the ovary. Gonado-somatic index was comparatively high during spawning seasons. This is a preliminary lesson on the reproductive biology and certain distinctive characters such as length-weight and food and feeding habits of Puntius amphibius.

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Sex ratio of breeding Common toads (Bufo bufo) – influence of survival and skipped breeding

Amphibia-Reptilia ◽

10.1163/017353710x524705 ◽

2010 ◽

Vol 31 (4) ◽

pp. 509-524 ◽

Cited By ~ 16

Author(s):

Thomas Madsen ◽

Jon Loman

Keyword(s):

Sex Ratio ◽

Deterministic Model ◽

Breeding Site ◽

Breeding Population ◽

Bufo Bufo ◽

Adult Males ◽

Breeding Sites ◽

Lower Survival Rate ◽

Biased Sex Ratio ◽

Males And Females

AbstractAnuran sex ratio at breeding sites is typically male biased. Such sex ratios may be due to poor female survival, to females not breeding as frequently as males and/or to males becoming sexually mature earlier than females. In the present study, the first two factors are analyzed in a common toad (Bufo bufo) population in southern Sweden. Toads were captured, marked and recaptured at the breeding site during 5 years. Within season capture patterns were analyzed using the Jolly-Seber model and among-year captures using the Closed robust design model. Population estimates of males and females yielded an among year variation in breeding population sex ratio, ranging from 16% to 34% females. On average, 41% (proportion adult alive but not breeding) of the females skipped breeding seasons, whereas the corresponding estimate for males was less than 5%. Yearly survival averaged 42% for adult female and 63% for adult male toads. First year adult males and females had a lower survival rate than older toads. Our results demonstrate that both a female biased mortality rate and a higher proportion of skipped breeding in females contribute to the observed male biased sex ratio. However, a deterministic model suggests other factors may also be involved to obtain this degree of male biased sex ratio, the most likely being that females mature at a later age than male toads.

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Studies on the maize stem borer, Busseola fusca (Lepidoptera: Noctuidae) and its major parasitoid, Dolichogenidea fuscivora (Hymenoptera: Braconidae), in eastern Ethiopia

Bulletin of Entomological Research ◽

10.1017/s0007485300037275 ◽

1997 ◽

Vol 87 (3) ◽

pp. 319-324 ◽

Cited By ~ 4

Author(s):

K. Yitaferu ◽

A. K. Walker

Keyword(s):

Sex Ratio ◽

Busseola Fusca ◽

Stem Borer ◽

Egg Laying ◽

Wet Season ◽

Single Female ◽

Eastern Ethiopia ◽

Larval Parasitoid ◽

Males And Females ◽

Lepidoptera Noctuidae

AbstractStudies on the lepidopterous stem borer, Busseola fusca (Fuller) and its major larval parasitoid, Dolichogenidea fuscivora Walker were carried out in the field and the laboratory in eastern Ethiopia. Larvae of B. fusca are also parasitized in the field by the braconid, Bracon sesamiae Cameron and the sarcophagid, Sarcophaga sp., but in low numbers. Parasitism of B. fusca by D. fuscivora is as high as 71% during the dry season (November-March) and approximately 18% in the wet season (June-September). Dolichogenidea fuscivora is active throughout the year. In the laboratory it requires nearly 26 days at 24 ± 1°C to complete the development of one generation (egg to egg laying). Longevity of adults is affected by the availability of food and water. Mating and oviposition reduced the life spans of males and females, respectively. Sixty five to 75 larvae emerged from eggs laid by a single female. The sex ratio ranged from 1:1 to 7:1 (female:male), the average being 5:1.

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Fecundity and Gonado-somatic Index of Trichiurus lepturus (Linnaeus, 1758) Along the Zamboanga del Norte Coast

International Journal of Emerging Research in Management and Technology ◽

10.23956/ijermt.v6i7.196 ◽

2018 ◽

Vol 6 (7) ◽

pp. 120

Author(s):

Ma. Dulce C. Guillena

Keyword(s):

Sex Ratio ◽

Stock Assessment ◽

Chi Square ◽

Moon Phases ◽

Ovary Weight ◽

Moment Coefficient ◽

Trichiurus Lepturus ◽

Significant Difference ◽

The Relationship ◽

Somatic Index

Gonado-somatic index and fecundity are tools for measuring the sexual maturity and ability of animals to reproduce. This study investigates the reproduction of Trichiurus lepturus. Specifically, this aimed to determine the sex ratio, the GSI, the relationship between fecundity and total length, fecundity and total weight, fecundity and ovary weight. The Descriptive Method of research was used. Percentage and chi-square was utilized in determining the percentage of occurrence and sex ratio respectively. Pearson r Product Moment Coefficient of Correlation was used to determine the relationships of the parameters. The study revealed that females outnumbered males and the sex ratio for different month showed significant difference. Spawning season was observed to occur in November and December as revealed in its GSI values and it synchronized with the full and new moon phases. Fecundity is positively correlated with body weight, body size, and ovary weight where ovary weight is observed to be the best index for fecundity. The results of this study could be used further for formal stock assessment of cutlassfish fishery.

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